What does that mean?

[Unearthlybrutal]

void OnStart()
{
ShowEnemyPlayerPosition("Grunty1");
AddUseItemCallback("", "Key_1", "castle_1", "KeyOnDoor", true);
AddEntityCollideCallback("Player", "ScriptArea_1", "CloseDoorFunc", true, 1);
}


void CloseDoorFunc(string &in asParent, string &in asChild, int alState)
{
SetSwingDoorLocked("castle_1", true, true);
}

void KeyOnDoor(string &in item, string &in door)
{
SetSwingDoorLocked("castle_1", false, true);
PlaySoundAtEntity("", "unlock_door", "castle_1", 0, false);
RemoveItem("Key_1");
}

void OnEnter()
{

}

void OnLeave()
{

}